That's a good point. But there are throughput considerations at the boundaries to the things that the brain wants to control. It makes most sense to centralize

That's a good point. But there are throughput considerations at the boundaries to the things that the brain wants to control. It makes most sense to centralize logic, and to delegate specialized control out to subsystems only where those specializations are relevant. Essentially making interfaces for control of appendages into APIs where the finer control logic is hidden from the main orchestrator. Exceptions exist where extra control at high levels is warranted (e.g. digits).